Identification of Root Rot Pathogens, Biological Control, and the Mechanism Analysis Underlying Polygonatum kingianum Response to Pathogen Stress

Root rot seriously threatens the growth of rhizomatous medicinal plants and crops. In this study, Fusarium oxysporum (Fo), Fusarium redolens (Fr), and Aspergillus awamori (Aw) were isolated and identified from diseased Polygonatum kingianum. Among them, Aw was identified as the main pathogen causing root rot, which was found for the first time, and exhibited significantly stronger pathogenicity than Fr and Fo. Lignin, flavonoids, isoflavones, the TCA cycle, and plant-pathogen interaction were involved in P. kingianum’s response to Aw infection. After Aw infection, the genes encoding PAL, PR1, MPK, and POD, along with corresponding enzyme activities, were significantly upregulated. PkPR1 was analyzed to enhance resistance against Fusarium and Aspergillus by gene overexpression. PR1, PAL, and POD regulate plant immune response through hypersensitivity and cell wall reinforcement. Antimicrobial agents, melatonin, and camphor oil demonstrated effective inhibition of Fusarium and Aspergillus. This study provides a foundation for the response mechanism of plants to pathogens, effective biological control, and resistance breeding strategies.